nVidia driver causes flickering viewport background
After about a year with the same issue, I found a solution: use Blender in REAL fullscreen mode. By that, I mean, do not use it with maximized window, go to Window > Toggle Window Fullscreen. This solved the problem both in Blender 2.79b and in 2.80.

I dunno if we have the same machine, I'm using an Acer Aspire-E5, but it uses the same graphics card, 940MX.

I feel like this is some sort of conflict between it and the integrated graphics card, where when idle, it uses the Intel card. This would explain this bug, and another one I was getting recently in 2.79b, were the interface would not show what was really happenning currently and show still images of stuff that happenned.

`Putting the software in fullscreen may tell the NVIDIA card that it can take full control of it, so those bugs don't happen.